Groundwater depletion

There is a tendency of groundwater resources getting scarcer over the years. On Basanti Island tube wells are drilled extremely deep, typically around 300 meters, in order to extract potable water. At some locations the wells do not have drinking water in the dry season, some places it is too salt and in some locations they do not potable groundwater resource at all. At the neighbouring island, Gosaba, they have almost no groundwater resource and must rely on dirty surface water.

Traditionally farmers used to irrigate their fields once a year in the dry season with water from their ponds. This practise is changing at rapid speed these years to irrigation with tube well water drawn from about 150-200 meters in Basanti. It is done by electric or diesel pumps and the result is a dramatic increase in extractions of groundwater. The government of India promotes an intensification of agriculture in West Bengal. However, if the groundwater is overexploited, there is a severe risk of salt water intrusion from the sea to the potable water reservoirs; a phenomenon that is close to irreversible, meaning the drinking, cooking and irrigation groundwater resource is practically destroyed. Further to this problem is that the groundwater that flows to Sandeskhali, Basanti and Gosaba is to a large degree limited by extraction upstream to Kolkata. All in all the groundwater in the three project areas are threatened.

A proper understanding of the groundwater resource is important in order to meet an increasing demand, but also in order to formulate future development and management strategies. We are monitoring the groundwater levels and doing various other assessments in order to understand the problems in detail.